A rotary electromechanical switch is generally defined as a device that has a rotating shaft connected to one terminal capable of making or breaking a connection to one or more other terminals. A rotary electromechanical encoder includes the overall characteristics of a rotary switch, but has additional mechanical movements. In any case, a user typically manipulates the switch to manually select a circuit.
Rotary switches and encoders are often mounted upon panels and other supporting structures in order that a user may control an electrical device. It is common for a portion of the switch to be on one side of the panel (the user side) and another portion of the switch to be on the other side of the panel (the inside). In many instances, the only portion of a switch that is on the user's side of the panel is a section of the shaft and a knob or other actuating means. Generally, the bulk of the switch is on the inside of the panel. For many years this type of configuration was sufficient, but over time the size of electrical devices has become increasingly smaller and there has become a need to reduce the size of the switch—especially that portion on the inside of the panel.
In order to meet the needs of smaller devices having less room under the panel, the size of the components of the switches have also become smaller. Yet, because these switches are comprised in part of mechanical components, there remained a practical limit as to how small they could become while still remaining useful. There became a need for different designs rather than just a reduction in the size of the components. One such design is taught in U.S. Pat. No. 4,454,391 to Olsson (June 1984). Olsson describes a low profile dip switch used on an integrated circuit board in which the actuating member of the dip switch is set within the body of the switch. By reducing the vertical profile of the switch, a lower overall footprint may be achieved for a board. The switch design taught by Olsson, however, does not address design problems related to panel mounted switches. Another patent which addresses problems in the design of switches is described in U.S. Pat. No. 6,312,288 to Genz et al. (November 2001). Genz teaches a low profile combination switch and connector assembly. While the switch described by Genz may have resulted in a lower overall profile of the combined components, this switch still does not address problems of panel mounted switches, specifically those problems due to limited space under the panel.
U.S. Pat. No. 6,043,855 to Grave (March 2000) is directed toward switches that mount on a bezel surrounding an LCD which is located on an avionics panel in an aircraft. The '855 patent teaches a design in which the detent is at least partially positioned in the knob of the switch. Still, the design of the '855 patent has its shortcomings: the detent is housed by the knob such that if the knob were to be displaced, the switch would not function or would function improperly; the detent is not entirely within the knob; the design requires two springs; and the springs are mounted vertically adding to the overall vertical profile of the knob.
As electronic devices become even smaller, there is a need for more compact and efficient designs.